Estimates for the pre-contact populations of most native groups in California have varied substantially. (See Population of Native California.)Alfred L. Kroeber (1925:883) estimated the combined 1770 population of the Serrano, Kitanemuk, and Tataviam as 3,500, and their population in 1910 as about 150. A close study of genealogical records indicates that people of Tataviam descent survived into the twentieth century, although most had lost their traditional language. Tribal members continued to intermarry with other indigenous groups and with other ethnicities.[3]

The Spanish first encountered the Tataviam during their 1769-1770 expeditions. According to Chester King and Thomas C. Blackburn (1978:536), "By 1810, virtually all the Tataviam had been baptized at Mission San Fernando Rey de España." Like other indigenous groups, they suffered high rates of fatalities from new infectious diseases brought by the Spanish, as they had no immunity (medical). As of 2015, the Tataviam people are trying to continue and maintain a tribal government. Although the Tataviam use to be referred to as the Mission Indians of San Fernando, during the Spanish Missionaries, but as of the revolving time with the Mexican Government they have made many land grant treaties within the Tataviam territory. Following the commencement of California as a state, The United States Indian Affairs had decided to group the Tataviam with other Indian Villages in the same region, which is now Fort Tejon Indian Reservation. [4]